Lymphocytotoxic antibodies in systemic lupus erythematosus and clinically related diseases.

Sera from patients with systemic lupus erythematosus (SLE) and clinically related diseases were examined for cold-reactive lymphocytotoxic antibodies (LCA). The incidence of LCA was significantly increased in SLE (93%), discoid lupus (50%), and "lupus-like" syndromes associated with congenital complement deficiencies (63%) as compared to normal controls (3%) and patients with drug-induced lupus (11%), mixed connective tissue disease (MCTD) (17%), and necrotizing vasculitis (19%). The diagnostic and pathogenetic implications of these differences are discussed.